Project Details
Projekt Print View

Gas bubbles in freshwater ecosystems: origin, fate, and bubble-mediated transport

Subject Area Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
Term from 2019 to 2023
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 422009572
 
Final Report Year 2024

Final Report Abstract

The project investigated the formation, composition and relevance of gas bubbles in aquatic ecosystems. Measurements in aquaculture ponds revealed the highest CH4 ebullition rates reported so far in the literature. Based on these data, we found a relationship between bubble size, gas composition, and bubbling rate. Bubble production rates in the sediment were controlled by organic matter quality rather than quantity. A method to quantify bubble size from bubble O2 content was developed and validated with direct measurements. The temporal dynamics of ebullition was studied on timescales of hours to seasons across different aquatic ecosystems and could be described by empirical models. For the first time, we showed that storage of gas bubbles in the sediment can be an important component in basin-scale CH4 budgets and a modulator of ebullition dynamics. We further found that bubbles transport substantial amounts of particulate matter of variable composition from the sediment to the water surface. By analyzing a large dataset, we could show that O2 ebullition depends both on bubbling rate and bubble composition. The composition of photosynthetic bubbles forming on macrophytes were quantitatively investigated in laboratory experiments. Based on these measurements, we developed theoretical approaches for predicting the gas composition of these bubbles.

Publications

 
 

Additional Information

Textvergrößerung und Kontrastanpassung